問題一覧
1
Chromosomes are replicated during the _____ phase
S
2
If a cell contains 20 chromosomes during 62, it will have 40 chromosomes during S.
False
3
The karyotype of a normal human male would show a total of 23 pairs of homologous chromosomes.
False
4
Which of the following statements regarding the G (first gap) phase of the eukaryotic cell cycle is NOT true?
If environmental conditions are favorable during the G phase, G cyclins are degraded causing the cell to prepare to replicate its DNA.
5
Homologous chromosomes are identical copies of each other
False
6
Consider an organism whose diploid karyotype shows it to have a total of 60 chromosomes. How many chromosomes would be contained in the sperm of this organism?
30
7
At prometaphase, the sister chromatids are organized into a single row in the center of the cell.
False
8
Which of the following is NOT a part of the mitotic spindle apparatus in plants?
centrioles
9
Colchicine is a toxin that binds to tubulin proteins and prevents microtubules from elongating. What effect might this have on dividing cells?
Sister chromatids will not be properly separated into separate daughter cells.
10
Which of the following statements about sister chromatids is TRUE?
Sister chromatids are exact copies of each other and are formed just prior to cell division.
11
Place the following events of mitosis in the correct order. I. Sister chromatids align on the metaphase plate. II. The cleavage furrow forms. III. The nuclear membrane breaks up. IV. Sister chromatids begin to condense. V. Sister chromatids separate.
IV, III, I, V. II
12
The centromere
Is a region of DNA where sister chromatids associate.
13
The process by which haploid cells are produced from diploid cells is called
meiosis
14
Mitotic cell division is never used by organisms as a means of reproduction.
false
15
Why must the life cycle of sexually reproducing species alternate between haploid and diploid stages?
Meiosis must occur at some point in the life cycle to prevent a doubling of chromosomes in each generation.
16
A cell undergoing meiosis that contains sister chromatids may be either haploid or diploid.
True
17
At the end of meiosis I
the cells are haploid and the homologous pairs are in separate cells.
18
For any given species, cells in metaphase II of meiosis would contain 2× more genetic material than cells in metaphase of mitosis.
False
19
If both synapsis and crossing over of non-homologous chromosomes occurred, what would be the expected result?
A reciprocal translocation
20
Sexual life cycles include both haploid and diploid stages
True
21
The life cycle of a sexually reproducing multicellular organism must include which processes?
mitosis, meiosis, and fusion of the gametes.
22
You prepare the first ever karyotype of an endangered species of frog. Upon examination you find that all the chromosomes are metacentric. This is going to make it difficult to identify
both the pand q arms of the chromosome.
23
Most human embryos that are aneuploid
are spontaneously aborted in the first trimester.
24
A plant has a reciprocal translocation between two chromosomes. It is heterozygous for this translocation, i.e., one set of chromosomes is normal, without the translocation. What effect can you be sure that this translocation has on the health and fertility of the plant?
The plant will make some normal gametes (with the full complement of DNA) and some abnormal gametes (without the full complement of DNA).
25
When a gamete that is lacking a sex chromosome due to nondisjunction has fused with a gamete carrying an X chromosome, this type of abnormality leads to ____
turner syndrome